Can a large metropolis sustain complex herpetofauna communities? An analysis of the suitability of green space fragments in Rome

Abstract

Urban areas are primary causes of species' range fragmentation and reduction. However, relatively few studies have attempted to describe the habitat variables influencing the diversity and conservation of amphibians and reptiles, particularly in Mediterranean Europe and in large metropolitan areas. We explored this broad conservation ecology problem by studying the richness and diversity patterns in relation to a suite of six independent habitat variables in Rome, one of the most ancient cities of the world. We considered all the green remnant areas (n = 62) of Rome, ranging 1 to 41000 ha in size, which are interspersed within a sea of urbanized matrix. A total of 10 amphibian and 15 reptile species were studied. Their presence/absence patterns were assessed and the effects of the various habitat variables on each species were predicted by a logistic regression model. A total of 1261 presence records (404 amphibians and 857 reptiles) were analysed. Fragment size and wood size within each fragment did correlate significantly with the species richness of both amphibians and reptiles, and there was a clear threshold effect after 50 ha of wooded surface. The presence of water bodies positively affected the species distribution. One amphibian and three reptiles inhabited exclusively fragments 450 ha. The distance from the centre did not affect fragment species richness. The presence of most species of both amphibians and reptiles was positively influenced by the irregular versus circular shape of the wooded area. The legal protection of a given area did not influence the observed patterns but the total number of sheltered species. Overall, our study suggests that, in order to maintain the current diversity and population viability, it is necessary, in addition to water bodies' maintenance, to (1) preserve the wooded landscapes over 50 ha; (2) promote irregularly shaped increases in the wood surface; (3) maintain ecotonal boundaries.

How small cities affect the biodiversity of ground-dwelling mammals and the relevance of this knowledge in planning urban land expansion in terms of urban wildlife

“…This is clearly visible in review papers, where examples from smaller cities are very scarce (Niemelä and Kotze 2009;Faeth et al 2011;Aronson et al 2014;Bonthoux et al 2014). The possible reason behind favouring large cities in research is the fact that large metropolitan areas represent the peak of urbanization and therefore can be used as appropriate models to analyse the effects of habitat fragmentation in the extreme (Vignoli et al 2009). In consequence, the basic generalizations and laws of urban ecology have been formulated on the basis of large city studies.…”

Rural–urban gradient and land use in a millenary metropolis: how urbanization affects avian functional groups and the role of old villas in bird assemblage patterning

“…Large metropolitan areas may represent a peak of urbanization, even though they may include remnant green areas of variable sizes. The Municipality of Rome, Central Italy, is one of the western metropolitan areas with the highest proportion of green spaces (67 %), half of these being protected areas (Vignoli et al, 2009). Rome's millennial-old natural heritage includes an extraordinary high number of old villas, most deriving from the enclosure of the Roman countryside and estates, mainly located within the inner city area.…”

Landscape of amphibian diversity in Latium Region: peaks, valleys and gaps of conservation priority

“…With over 60% of surface area devoted to green spaces (half of them consisting of protected areas; Blasi et al 2001), the territory of Rome still represents the remnant "Campagna romana", a traditional mosaic landscape devoted to stock raising and homely agriculture (Celesti Grapow et al 2006), which preserved a certain amount of pristine biodiversity (i.e. Della Rocca et al 2005;Bologna et al 2007;Vignoli et al 2009). On the contrary, the nearby areas just southeast of Rome, where the "Campagna romana" landscape was transformed into intensive agriculture and industrialized areas, showed an observed and expected scanty amphibian richness.…”

“…Vignoli et al 2009), scorpions (Crucitti et al 1998), insects (Zapparoli 1997;Fattorini 2011), reptiles (Rugiero & Luiselli 2006Vignoli et al 2009;Maura et al 2011), birds (Cignini & Zapparoli 1996;Sorace 2001;Clergeau et al 2006) and small mammals (Sorace 2001;Amori et al 2009). This contradiction can be interpreted in two different ways.…”